Pinking in White Wines - A Review

Abstract

In the late 1960s, a phenomenon was discovered in white wines. It was noted that certain white wines turned pink in the bottle. This phenomenon was dubbed as pinking. Research was done on the pinking to establish its cause and effect. Analysis of SO 2 , pH and polyvinyl polypyrrolidone (PVPP) showed that a minimum of 45 mg/L of SO 2 were needed for the wine not to be susceptible to pinking. Tests on the decrease in pH showed that there was no increase in pink colour with a decrease in pH, which meant that monomeric anthocyanins were not the cause of pinking. Recent research claims that malvidin-3-Oglucoside is the most abundant monomeric anthocyanin found in pinked wines and could be the cause of pinking. This led to the theory that phenols contribute to pinking susceptibility, and this was accepted as fact in recent years. The establishment of a pinking assay in 1977 made the testing for pinking easier and cheaper for winemakers. The sales of PVPP increased as winemakers worked preventatively with their wine to decrease susceptibility to pinking. This review attempts to describe the history of pinking, the establishment of the assay, as well as to describe factors that could lead to pinking susceptibility in white wines.

Alternative Methods for Measuring the Susceptibility of White Wines to Pinking Alteration: Derivative Spectroscopy and CIEL*a*b* Colour Analysis

“…The classic method of inducing oxidation of white wines for measuring the pinking susceptibility varies according to the country concerning the volume of wine used and the hydrogen peroxide amount added for oxidation [ 27 ]. Nevertheless, all the methods are time consuming, normally taking 24 h to complete.…”

Investigation of the appearance and elimination of pinking coloration in white wines

“…Prevention and elimination of "pinking" involve the treatment of wine materials with agents that can prevent oxidation. The most common ways to prevent pink color are the use of ascorbic acid before bottling or treatment of wines by PVPP or potassium caseinate [1,2], which can adsorb phenolic compounds responsible for color change. The research of these authors was aimed at determining the effect of certain substances on the elimination or prevention of "pinking".…”

“…In [1], it is noted that the degree of ripening affects the content of phenolic substances in grape. An increase in the content of phenolic substances can lead to an increase in anthocyanins, which belong to the group of phenolic compounds, and may cause a pink tinge of white wines [5].…”

“…In the scientific world, this phenomenon is called "pinking". This problem appeared about 30-40 years ago and winemakers around the world have been taken it seriously [1][2][3]. During this period, scientists from different countries were finding out the causes of pinking.…”

Sensory Evaluation of Pinked Sauvignon Blanc Wines

“…Pinked wines are defined as white wines that show a pink colouration under certain winemaking conditions and were first described by Singleton and Esau in 1969. Many white cultivars are affected by the pinking phenomenon, including Albariño, Chardonnay, Chenin blanc, Crouchen, Doradillo, Garnatxa blanca (Grenache), Grüner Veltliner, Macabeo, Muscat Gordo Blanco, Pálava, Palomino, Parellada, Pinot Gris, Riesling, Sauvignon blanc, Semillon, Síria, Sultana, Thompson Seedless, White Riesling and Xarel•lo (Simpson, 1977a;Tobe, 1983;Jones, 1989;Lamuela-Raventós et al, 2001;Andrea-Silva et al, 2014;Nel et al, 2020). Simpson (1977a) describes pinking as a troublesome discolouration that develops after normal winemaking production.…”